The goal of the paper was to examine the efficiency of executive functions in children with attention deficit/hyperactivity disorder (ADHD). Fifteen ADHD children and 24 non-ADHD children were tested in the task-switching test/pencil test of The General Test Battery of Children's Cognitive Abilities, ADHD children showed substantially more perseverative errors than non-ADHD children did, but children with and without ADHD had equal switching errors. These findings support deficit of executive functions in children with ADHD.